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Патент USA US3046373

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July 24, 1962
G. w. REYNOLDS
3,046,363
BILATERAL PARAMETRIC AMPLIFIER
Filed 001',- 23, 1959
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Patented July 24}, 1962
2
3,01%,3d3
BILATERAL PARAh/TETRTC AMPLIFIER
George W. Reynolds, (Zorona Del Mar, Caiitl, assignor
to Standard Coil Products (30., Inc, Melrose Park, Ill,
a corporation of Illinois
Filed (Bot. 23, 1959, Ser. No. 848,280
11 Claims. (Cl. 179-l7il)
The instant invention relates to parametric ampli?ers
Another object is to provide a bilateral ampli?er circuit
utilizing a variable parameter or parametric principle of
ampli?cation.
Still another object is to utilize a semi-conductor diode
as a variable impedance storage means in a bilateral
parametric ampli?er.
The foregoing objects as well as other objects of the
instant invention shall become readily apparent after
reading the following description of the accompanying
in general and more particularly to a parametric ampli?er
‘drawings in which:
having bilateral characteristics.
The variable parameter or parametric principle of ampli
prising the bilateral parametric ampli?er of the instant
FIGURE 1 is a schematic diagram of the circuit com
invention.
?cation is characterized by an arrangement in which a
FIGURE 2 is a graph illustrating the variation in
variable impedance energy storage element, such as a
capacitor or inductor, is coupled to two resonant circuits. 15 capacitance of the energy storage means as a function of
voltage applied thereto.
If the impedance of the energy storage element is varied
in a predetermined manner energy can be transferred
Now referring to the ?gures, bilateral parametric are-pli
?er it) comprises two substantially identical circuits feed
from a source driving the energy storage element to the
ing opposite ends of center tapped signal coupling coil
?elds of the resonant circuits. The signals derived from
the energy source are mixed with the signals to be ampli 20 12 whose center tap 13 is grounded. The circuit con
nected to the left end of coupling coil 12 comprises a
?ed in a manner such that an extremely low noise ?gure
variable impedance energy storage means, in the form
and a wide bandwidth are obtained.
of semi-conductor diode 14, having one terminal con
In general, ampli?ers are unilateral devices that is, a
‘nected to the left hand end of coupling coil 12 and the
signal applied to the input will appear ampli?ed at the
output and a signal applied to the output will either not
appear at the input or will appear with a greatly re
duced magnitude. On the other hand, a bilateral ampli
?er is capable of accepting signals at either the input or
output and producing an ampli?ed signal at the other.
Signals may be applied to both input and output simul
taneously and ampli?cation obtained for both signals.
However, in this case the two applied signals cannot be at
precisely the same frequency.
A bilateral ampli?er having a low noise ?gure and
other terminal connected through circuit conductor 15
to one terminal of inductor 16 whose other terminal is
connected to circuit conductor 17. One terminal of milli
ammeter 18 is connected to circuit conductor 17 and the
other terminal is connected to the negative terminal of
biasing voltage source 19 whose positive terminal is
grounded.
‘Feed-through capacitors 20, 21 are associated with con
ductors 15, 17 respectively. The latter capacitor 21 is
simply an yR.-F. by-pass means which eifectivey places
the
bottom end of inductor 16 at grounded potential
35
wide bandwidth is suitable for use in a two way data
for R.~F. purposes. Capacitor 20 is considerably smaller
transmission system which utilizes a single cable. This
type of bilateral ampli?er may also be utilized for two
way communication over a single cable without any com
plicated switching or ?ltering being required.
than capacitor 21 and combines with inductor 16 to form
an input-output circuit which is tuned to the frequency
of the signal which is to be ampli?ed. This signal is ap
plied between tap 22 and inductor 1'6 and ground.
Brie?y, the device of the instant invention comprises 40 The signal to be ampli?ed passes from input-output
two circuits which are arranged substantially symmetrical
ly about a center tapped signal coupling coil. Each cir
cuit comprises an input-output circuit, tuned to the sig
nal frequency, which feeds a variable impedance energy 45
storage means. In the case illustrated, the energy storage
means comprises a semiconductor diode whose impedance,
in the operating range chosen, appears as a capacitive
reactance which varies as a function of the voltage ap
plied across the diode.
The principal source of voltage variation is obtained
from a local oscillator, with the energy of the local oscil~
lator being transferred through the coupling coil to the
energy storage means. The signal to be ampli?ed and
circuit 16, 2% through diode 14 and coupling coil 12 to
transfer circuit 23, comprising conductor 24 and capacitor
25. The transfer circuit 23 is tuned to a frequency which
is the sum of the signal frequency and the frequency of
local oscillator 26 whose‘r’energy is transferred through
inductor 27 and coupling coil 12 to transfer circuit 23.
The circuit connected to the right hand end of coupling
coil 2% is substantially identical to the circuit connected
to the left hand end of coupling coil 12 and comprises
variable impedance energy storage means in the form of
semi-conductor diode 30. One terminal of diode 30 is
connected to the right hand end of coupling coil 12 and
the other end is connected to circuit conductor 31. Con
the local oscillator signal are mixed in the energy storage 55 ductor 31 is connected through feed-through capacitor
means with the sum frequency being transferred through
32 to one end of inductor 33 whose other end is con
the coupling coil to a transfer circuit which is tuned to
nected to circuit conductor 35 having feed-through capaci
the sum frequency.
tor 34 associated therewith. Circuit conductor 35 is con
.A second mixing operation takes place at the variable
impedance storage means of the other symmetrically
arranged circuit with the local oscillator and sum fre
quency signals combining to produce a difference fre
quency signal which is at the same frequency as the sig
nal to be ampli?ed. This difference frequency appears
as the ampli?ed output at the input-output circuit of the
latter symmetrically arranged circuit.
In the same manner a signal applied to the input-out
put circuit of the second symmetrically arranged circuit
nected to one terminal of milli-ammeter 36 whose other
terminal is connected to the positive terminal of biasing
voltage source 37 having a grounded negative terminal.
Just as feed-through capacitor 21 was and R-F by-pass
capacitor so too is feed-through capacitor 34. Capacitor
32 combines with inductor 33 to form an input-output
circuit which is tuned to substantially the same frequency
as the input-output circuit which is comprised of elements
16 and 20. Not only do feed-through capacitors 'Ztl and
32 function as tuning elements for the input-output cir
will appear as an ampli?ed signal at the input-output cir
cuits but they also act as short circuits to ground for
cuit of the ?rst symmetrically arranged circuit.
Accordingly, a primary object of the instant invention
isto provide a novel bilateral ampli?er circuit.
the local oscillator signals. Thus, the local oscillator
signals coupled into coil 10 will have two series circuits
through which components of current will flow. These
3,046,363
Ll
(.3
circuits comprise diodes 14-, 3t} and their associated feed
through capacitors 29, 32, respectively.
The sum frequency signal appearing in tuned transfer
circuit 23 is transferred out through coupling coil 13 and
appears at diode 30 where it is mixed with a signal from
local oscillator 26.
The difference frequency signal
produced by the mixing operation appears as an ampli?ed
signal taken between tap 33 of inductor 33 and ground.
scribed circuit, was on the order of two corresponding
to a voltage gain of approximately 6 db.
Insofar as critical frequencies are concerned in the bi
lateral parametric ampli?er, the frequencies applied at
the two input terminals 22, 33 cannot be identical. The
proximity of the two frequencies is determined by the
selectivity of the devices which are used at the two respec
tive output terminals to separate the signals. Using spe
Diodes 14 and 31'} are of the type manufactured by
ci?c numbers, if an 83 me. ‘modulated signal of 3 me.
Hughes Aircraft Company designated HP 2040, which are 10 bandwidth is applied at terminal 22, it will appear at ter
designed speci?cally for parametric ampli?ers. Each of
minal 38 in an ampli?ed form, and if at terminal 38 we
the diodes has a characteristic such that when it is back
have a modulated signal of 87 mc., it will appear at ter
biased it behaves as a capacitor with the value of capaci
minal 22 in an ampli?ed form, and at each terminal a de
tance being a function of the voltage existing across the
diode. The diodes are further characterized by exhibit
ing a low spreading resistance and a relatively small value
of back-bias capacitance.
Diodes 14 and 30 are connected in tandem or series
aiding relationship. The voltages of ‘biasing sources 19
and 37 are adjusted so that the quiescent D.C. currents
?owing through diodes 14 and 39 are in the order of 5
to 10 micro-amperes. With this magnitude of DC. cur~
rent ?owing, the diodes 14, 30 are operating essentially
in the middle of the non-linear voltage capacitance curve
illustrated in FIGURE 2. The capacitance of the diodes
14, 30 is varied at the frequency of the signal generated
vice which has su?icient selectivity to separate the side
bands of the 83 mc. modulated signal and the 87 mc.
modulated signal must be used.
Although I have here described preferred embodiment
of my novel invention, many variations and modi?ca
tions will now be apparent to those skilled in the art, and
I therefore prefer to be limited, not ‘by the speci?c dis
closure herein, but only by the appending claims.
I claim:
1. An ampli?er for transmitting signals with gain in
both a forward and a reverse direction; said ampli?er
comprising a ?rst signal input-output circuit for input sig
nals in said forward direction and output signals in said
by local oscillator 26. Care must be taken that the volt
reverse direction, a second signal input-output circuit for
age sum of the local oscillator and signal to be ampli
input signals in said reverse direction and output signals
?ed will not drive the diodes 14, 36 into either forward
in said forward direction, and circuit means extending
conduction or Zener breakdown.
30 between said input-output circuits; said circuit means com
The change in diode capacitance as a function of volt
prising a signal coupling device, a ?rst variable impedance
age is best understood by the reference to the graph of
energy storage means interposed between said coupling
FIGURE 2. The biasting voltage sources 19 and 37 are
device and said ?rst input~output circuit a second variable
adjacent so that the quiescent D.C. currents ?owing
impedance energy storage means interposed between said
through diodes 14, 3t} establishes point A on curve B
coupling device and said second signal input-output cir
as the operating point about which the capacitance value
cuit, a local oscillator means operatively positioned to
will vary. The signal voltage F generated by local oscil
supply energy to said coupling device, and a transfer
lator 26 causes the capacitance value of diodes 14 and
30 to vary through the range AC about operating point
A as a mid point.
In looking at circuit 10 it is seen that there is essen
tially complete symmetry. Overall experimental results
show that if a signal is applied between terminal 22 and
ground an ampli?ed version of that signal will appear at
terminal 38 and ground. The signal that is coupled in
at terminal 22 will appear in tuned transfer circuit 23
as the sum frequency and the gain existing at this point,
if no straight parametric ampli?cation is present, is ap
proximately equal to the ratio of the sum of the local
oscillator frequency plus the signal frequency divided by
the signal frequency.
In an actual experiment the signal frequency was 85
megacycles and the local oscillator frequency was 1000
megacycles. Therefore, under these conditions the theo
retical maximum gain existing to the point of transfer
circuit 23 was the ratio of 1085 divided by85 which is ap
proximately 13. However, a certain amount of para
metric ampli?cation is present so that the gain of this
point is actually greater than the calculated gain. Diode
means operatively positioned to receive energy from and
transfer energy to said coupling device; said ?rst input
40 output circuit comprising means tuned to a ?rst frequency,
said local oscillator being tuned to a second frequency,
and said transfer means comprising means tuned to a
third frequency which is the sum of said ?rst and said
second frequencies.
2. An ampli?er for transmitting signals with gain in
both a forward and a reverse direction; said ampli?er
comprising a ?rst signal input-output circuit for input
signals in said forward direction and output signals in said
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals
in said forward direction, and circuit means extending be
tween said input-output circuits; said circuit means com
prising a signal coupling device, a ?rst variable impedance
energy storage means interposed between said coupling
device and said ?rst input-output circuit a second variable
impedance energy storage means interposed between said
coupling device and said second signal input-output cir
cuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer
30 serves primarily as a non-linear capacitance mixer
means operatively positioned to receive energy from and
between the local oscillator frequency and the sum fre 60 transfer energy to said coupling device; each of said vari
quency appearing in transfer circuit 23 to produce a
able impedance energy storage means comprising a semi
difference frequency. This difference frequency is then
conductor means.
coupled into input-output circuit 32, 33 to appear as out
3. An ampli?er for transmitting signals with gain in
put at terminal 38. The portion of the circuit to the
both a forward and a reverse direction; said ampli?er
65
right of transfer circuit 23 should have a down-conver
comprising a ?rst signal input-output circuit for input sig
sion loss that is approximately equal to the up-conversion
gain existing in the circuit to the left of transfer circuit
23. The fact that gain exists for the overall circuit is
nals in said forward direction and output signals in said
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals
due to the fact that some of the lower side band, that 70 in said forward direction, and circuit means extending be
is the local oscillator frequency minus the signal fre
tween said input-output circuits; said circuit means com
quency exists and this causes parametric ampli?cation
prising a signal coupling device, a ?rst variable impedance
to be present thus giving more gain between input 22
energy storage means interposed between said coupling
and transfer circuit 23 than is predicted in theory. The
device and said ?rst input-output circuit a second variable
overall gain, as measured in the laboratory for the de 75 impedance energy storage means interposed between said
3,046,363
6
coupling device and said second signal input-output cir
transfer energy to said coupling device; each of said
variable impedance energy storage means comprising a
cuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer
means operatively positioned to receive energy from and
transfer energy to said coupling device; each of said vari
able impedance energy storage means comprising a semi
semi-conductor means; each of said semi-conductor means
constructed to present a capacitive reactance which varies
as a function of voltage applied to said semi-conductor
means; each of said semi-conductor means comprising a
conductor means; each of said semi-conductor means
constructed to present a capacitive reactance which varies
as a function of voltage applied to said semi-conductor
tionship; means supplying a DC. quiescent operating cur
rent for both of said diodes; said coupling device com
means.
4. An ampli?er for transmitting signals with gain in
diode; said diodes being connected in series aiding rela
10 prising a coil having a center-tap; conductor means con
nected to said center-tap and forming a portion of a
both a forward and a reverse direction; said ampli?er
circuit for the DC. quiescent operating currents of said
comprising a ?rst signal input-output circuit for input
signals in said forward direction and output signals in
said reverse direction, a second signal input-output cir
cuit for input signals in said reverse direction and output
signals in said forward direction, and circuit means extend
ing between said input-output circuits; said circuit means
comprising a signal coupling device, a ?rst variable imped—
diodes.
ance energy storage means interposed between said cou
plin g device and said ?rst input-output circuit a second var
able impedance energy storage means interposed between
7. An ampli?er for transmitting signals with gain in
both a forward and a reverse direction; said ampli?er
comprising a ?rst signal input-output circuit for input sig
nals in said forward direction and output signals in said
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals
20 in said forward direction, and circuit means extending be
tween said input-output circuits; said circuit means com
prising a signal coupling device, a ?rst variable impedance
energy storage means interposed between said coupling
device and said ?rst input-output circuit a second variable
circuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer 25 impedance energy storage means interposed between said
coupling device and said second signal input-output cir
means operatively positioned to receive energy from and
cuit, a local oscillator means operatively positioned to
transfer energy to said coupling device; each of said
variable impedance energy storage means comprising a
supply energy to said coupling device, and a transfer
means operatively positioned to receive energy from and
semi-conductor means; each of said semi-conductor means
constructed to present a capacitive reactance which varies 30 transfer energy to said coupling device; each of said vari
said coupling device and said second signal input-output
diode; said diodes being connected in series aiding rela
able impedance energy storage means comprising a semi
conductor means; each of said semi-conductor means con
structed to present a capacitive reactance which varies as
tionship.
a function of voltage applied to said semi-conductor
‘as a function of voltage applied to said semi-conductor
means; each of said semi-conductor means comprising a
5. An ampli?er for transmitting signals with gain in 35 means; each of said semi-conductor means comprising a
diode; said diodes being connected in series aiding rela
both a forward and a reverse direction; said ampli?er
tionship; means supplying a DC. quiescent operating cur
comprising a ?rst signal input-output circuit for input sig
rent for both of said diodes; said coupling device com
nals in said forward direction and output signals in said
prising a coil having a center-tap; conductor means con
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals 40 nected to said center-tap and forming a portion of a cir
cuit for the DC. quiescent operating currents of said
in said forward direction, and circuit means extending be
diodes; each of said input-output circuits comprising a
tween said input-output circuits; said circuit means com
tuned circuit including a feed-through capacitor as a
prising a signal coupling device, a ?rst variable impedance
energy storage means interposed between said coupling de
tuning element thereof.
8. An ampli?er for transmitting signals with gain in
vice and said ?rst input-output circuit a second variable 45
both a forward and a reverse direction; said ampli?er
impedance energy storage means interposed between said
coupling device and said second signal input-output cir
cuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer
means operatively positioned to receive energy from and
transfer energy to said coupling device; each of said vari
able impedance energy storage means comprising a semi
comprising a ?rst signal input-output circuit for input
signals in said forward direction and output signals in said
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals
in said forward direction, and circuit means extending
between said input-output circuits; said circuit means
comprising a signal coupling device, a ?rst variable im
conductor means; each of said semi-conductor means
pedance energy storage means interposed between said
constructed to present a capacitive reactance which varies
as a function of voltage applied to said semi-conductor 55 coupling device and said ?rst input-output circuit a second
variable impedance energy storage means interposed be
means; each of said semi-conductor means comprising a
diode; said diodes being connected in series aiding rela
tionship; means supplying a DC. quiescent operating cur
rent for both of said diodes.
6. An ampli?er for transmitting signals with gain in
both a forward and a reverse direction; said ampli?er
tween said coupling device and said second signal input
output circuit, a local oscillator means operatively posi
tioned to supply energy to said coupling device, and a
transfer means operatively positioned to receive energy
from and transfer energy to said coupling device; said
?rst input-output circuit comprising means tuned to a
com-prising a ?rst signal input-output circuit for input
?rst frequency, said local oscillator being tuned to a sec
signals in said forward direction and output signals in said
ond frequency, and said transfer means comprising means
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals 65 tuned to a third frequency which is the sum of said ?rst
and said second frequencies; each of said variable im
in said forward direction, and circuit means extending
between said input-output circuits; said circuit means com
pedance energy storage means comprising a semi-con
prising a signal coupling device, a ?rst variable impedance
energy storage means interposed between said coupling de
ductor means.
9. An ampli?er for transmitting signals with gain in
vice and said ?rst input-output circuit a second variable 70 both a forward and a reverse direction; said ampli?er
comprising a ?rst signal input-output circuit for input
impedance energy storage means interposed between said
signals in said forward direction and output signals in said
coupling device and said second signal input-output cir
reverse direction, a second signal input-output circuit for
cuit, a local oscillator means operatively positioned to
input signals in said reverse direction and output signals
supply energy to said coupling device, and a transfer
means operatively positioned to receive energy from and 75 in said forward direction, and circuit means extending be
3,648,863
8
7
tween said input-output circuits; said circuit means com
a capacitive reactance which varies as a function of volt
prising a signal coupling device, a ?rst variable impedance
energy storage means interposed between said coupling
age applied to said semi-conductor means.
device and said ?rst input-output circuit, a second variable
impedance energy storage means interposed between said
both a forward and a reverse direction; said ampli?er
coupling device and said second signal input-output cir
cuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer
11. An ampli?er for transmitting signals with gain in
comprising a ?rst signal input-output circuit for input sig
nals in said forward direction and output signals in said
reverse direction, a second signal input-output circuit for
input signals in said reverse direction and output signals
means operatively positioned to receive energy from and
in said forward direction, and circuit means extending be
transfer energy to said coupling device; said ?rst input 10 tween said input-output circuits; said circuit means com
output circuit comprising means tuned to a ?rst frequency,
prising a signal coupling device, a ?rst variable impedance
said local oscillator being tuned to a second frequency,
and said transfer means comprising means tuned to a third
frequency which is the sum of said ?rst and said second
frequencies; each of said variable impedance energy
energy storage means interposed between said coupling
device and said ?rst input-output circuit a second variable
impedance energy storage means interposed between said
coupling device and said second signal input-output cir
storage means comprising a semi-conductor means; said
cuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer
means operatively positioned to receive energy from and
both a forward and a reverse direction; said ampli?er
transfer energy to said coupling device; said ?rst input
comprising a ?rst signal input-output circuit for input sig 20 output circuit comprising means tuned to a ?rst frequency,
nals in said forward direction and output signals in said
said local oscillator being tuned to a second frequency,
reverse direction, a second signal input-output circuit for
and said transfer means comprising means tuned to a
input signals in said reverse direction and output signals
third frequency which is the sum of said ?rst and said
in said forward direction, and circuit means extending be
second frequencies; each of said variable impedance en
coupling device comprising a center-tapped coil'
10. An ampli?er for transmitting signals with gain in
tween said input-output circuits; said circuit means com
prising a signal coupling device, a ?rst variable impedance
energy storage means interposed between said coupling
device and said ?rst input-output circuit a second variable
impedance energy storage means interposed between said
coupling device and said second signal input-output cir 30
ergy storage means comprising a semi-conductor means;
each of said semi-conductor means constructed to present
a capacitive reactance which varies as a function of volt
age applied to said semi-conductor means; each of said
semi-conductor means comprising a diode; said diodes
being connected in series opposing relationship; means
supplying a DC quiescent operating current for both of
said diodes; said coupling device comprising a coil having
cuit, a local oscillator means operatively positioned to
supply energy to said coupling device, and a transfer
means operatively positioned to receive energy from and
a center-tap; conductor means connected to said center
transfer energy to said coupling device; said ?rst input
tap and forming a portion of a circuit for the DC.
output circuit comprising means tuned to a ?rst frequency,
said local oscillator being tuned to a second frequency,
quiescent operating currents of said diodes.
and said transfer means comprising means tuned to a
References Cited in the ?le of this patent
third frequency which is the sum of said ?rst and said
second frequencies; each of said variable impedance en
ergy storage means comprising a semi-conductor means; 40
each of said semi-conductor means constructed to present
UNITED STATES PATENTS
2,666,816
2,850,585
Hunter ______________ __ Jan. 19, 1954
Green _______________ __ Sept. 2, 1958
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